The present invention relates to an evaluating instrument for the automatic photometric analysis of liquid specimens in which reagents appropriate for the specific analysis are supplied in predetermined doses to the specimen to be measured, and in which the actual measurement is effected with instrument parameters adapted to the specific analysis.
Such evaluation instruments are used, in particular, for the analysis of body fluids such as blood, urine, etc., their purpose being to carry out a plurality of analyses within a short time and without the need for trained medical personnel.
Several such automatic analyzers are known. Thus, an instrument is known in which fluid to be analyzed is conducted through a labyrinth of flexible tubes, whereby a given number of different analyses are necessarily performed. This device has the disadvantage that a fixed path for the sample and a fixed sequence of analysis are pre-established so that it is not possible to select the number and sequence of the analyses as desired. The instrument can therefore not operate selectively.
An automatic analyzer is also known (Swiss Pat. No. 526,109) which operates with the use of punched cards and on which there are firmly arranged containers which contain in completely dosaged amount all reagents necessary for a given analysis as well as a reaction chamber. Each of these punch cards bears a coding. If a given analysis is to be carried out with a sample, the punched card in question is inserted into the evaluation instrument. There, a predetermined amount of specimen is injected into the reaction chamber, and at the same time all reagents present pass from their storage containers into the reaction chamber. The adjustment of the instrument parameters, and thus the measurement, takes place in accordance with the coding of the punched card. The measured value is stored on the punched card and subsequently evaluated.
Evaluation instruments of the latter type can operate selectively, but they are limited in their possibilities of application since it is not possible freely to select the reagents. Furthermore, their operation is expensive, since a separate punched card with completely predosed reagents is necessary for each individual measurement. Finally, the accuracy of the individual measurement is limited, due to the fact that each measurement must be carried out at a different reaction chamber, as a result of which homogeneity is not assured for light-penetration of specimen chamber walls, and a reduction of measurement light is possible.